This proposal seeks to evaluate adenovirus-based gene transfer vectors as a potential system for gene therapies of human retinitis pigmentosa and allied diseases. Experiments are designed to optimize gene transfer and expression in the mouse retina by adenoviral vectors. Issues regarding delivery methods, efficiency of gene transfer and expression, tissue specificity, stability of transgene in target cells, and local and systemic pathogenicity will be addressed. Transgene expression will be followed by histochemical staining of the reporter gene (lacZ) product, beta-galactosidase. Subsequently, functional gene constructs will be engineered into adenoviral vectors and introduced into the retinas of rd and rds mice to attempt rescue of photoreceptors from degeneration. The outcome will be assessed by histological examination and electroretinographic (ERG) testing. As a separate but related effort, a novel approach is proposed to identify the promoter/enhancer elements of the peripherin/rds gene and the beta-PDE gene so that these elements could be incorporated into gene constructs to achieve regulated expression in target cells. Information regarding such elements is not available for most photoreceptor specific genes at present. This approach utilizes in vitro transfer of putative promoter-reporter gene fusion constructs into retinal explants via a herpes virus-based amplicon vector. If developed successfully, it may prove to be a more rapid and much more cost effective method over transgenic mouse studies for similar purposes. Successful implementation of this proposal will produce valuable information and methods for developing gene therapies of retinitis pigmentosa and allied diseases.